Harris,  Franklin  I. 

The  action  of  ultraviolet 
light  on  certain  bacteria  in 
relation  to  specfic  absorption 
by  amino  acids 


"library 

-..  IRVINE^ 


\}f' 


•ilVERSlTY  OF  CALlFCRfllA  LIBRARY.  IRVlNt 


UNIVERSITY   OF   CALIFORNIA    PUBLICATIONS 

IN 

PATHOLOGY 

Vol.  2,  No.  21,  pp.  245-250  March  25,  1919 


THE  ACTION  OF  ULTRAVIOLET  LIGHT  ON 

CERTAIN  BACTERIA  IN  RELATION 

TO  SPECIFIC  ABSORPTION 

BY  AMINO  ACIDS 


BY 

FRANKLIN  I.  HARRIS  and  HUBBARD  S.  HOYT 


UNIVERSITY  OF  CALIFORNIA  PRESS 
BERKELEY 


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UNIVERSITY   OF   CALIFORNIA    PUBLICATIONS 

IN 

PATHOLOGY 

Vol.  2,  No.  21,  pp.  245-250  March  25,  I9I9 


THE  ACTION  OF  ULTRAVIOLET  LIGHT  ON 

CERTAIN  BACTERIA  IN  RELATION 

TO  SPECIFIC  ABSORPTION 

BY  AMINO  ACIDS 

BY 

FRANKLIN  I.  HAERIS  and  HUBBARD  S.  HOYT 
(From  the  Department  of  Pathology  and  Bacteriology,  University  of  Caiifornia) 


Within  recent  years  considerable  interest  has  been  shown  in 
the  study  of  the  ultraviolet  radiations  in  relation  to  their  toxicity 
for  living  protoplasm.  It  was  early  found  that  these  radiations 
exert  a  highly  toxic  influence  on  protoplasm  exposed  to  them. 
Henri,''  -  in  conjunction  with  various  co-workers,  has  done 
pioneer  work  in  this  field,  and  was  the  first  worker  to  point  out 
the  possibility  of  a  practical  application  of  this  subject,  namely, 
in  the  sterilization  of  various  substances  and  solutions.  Further 
work  on  the  germicidal  effect  of  ultraviolet  light  has  been  done 
by  Houghton  and  Davis,^  who  found  that  the  rays  produced  by 
the  Cooper-Hewitt  mercury  arc  exert  a  strong  bacterial  action 
on  various  species  of  bacteria,  including  spore  forming  organisms. 

The  action  of  these  radiations  was  recognized  as  a  photo- 
chemical process,  and  was  supposed  to  be  due  to  the  absorption  of 
the  rays  by  the  bacterial  protoplasm.  In  a  previous  report^-  ^ 
we  studied  this  phase  of  the  problem  and  proceeded  on  the  basis 
of  the  first  law  of  photochemical  action,  that  in  a  photochemical 
system,  to  be  effective,  the  rays  must  be  absorbed,  usually  by 
specific   constituents.     We   h.nve   further  shown   that   the   toxic 


246         University  of  California  Publk-atioiis  in  Pathologi)   [Vol.  2 

action  of  ultraviolet  light  obeys  this  law  and  is  due  to  the  absorp- 
tion of  the  rays  by  certain  constituents  of  all  living  protoplasm, 
namely,  the  tyrosine  and  phenylalanin  radicals  of  the  protein 
molecules.  These  two  acids  are  the  specific  absorbents  in  living 
protopla.sm  for  the  rays  of  the  mercury  arc. 

The  object  of  the  present  work  was  to  confirm  this  work, 
using  bacteria  as  a  biological  test,  and  further  to  study  the  rela- 
tive speed  of  absorption  of  the  ultraviolet  raj^s  by  the  protoplasm 
of  the  various  types  of  bacteria. 

jMethods 
Three   organisms   were   selected   as   typifying  thi-ee    general 
groups  of  bacteria,  which  are  classed  on  the  basis  of  the  posses- 
sion or  lack  of  protective  structures,  spores  and  capsules. 

1.  A  non-sporulating,  non-capsulated  organism,  Staphylo- 

coccus aureus. 

2.  A  sporulating.  non-capsulated  organism.  Bacillus  suh- 

tilis. 

3.  A   capsulated,   non-sporulating   organism,   B.    niucosus 

capsulatus. 

For  the  exposure  of  these  organisms  various  methods  were 
tried.  The  organisms  were  grown  on  agar  slants  for  twenty-four 
hours,  and  then  washed  off  with  sterile  0.85%  NaCl.  A  pre- 
liminary exposure  was  made  with  a  given  amount  of  each  saline 
suspension  exposed  directly  to  the  rays.  As  no  consistent  results 
were  obtained  by  this  method,  due  undoubtedly  to  the  absorption 
of  the  rays  by  the  upper  layers  of  the  bacterial  suspension,  this 
method  was  abandoned. 

A  number  of  plating  methods  were  then  tried,  ^lelted  agar 
was  poured  at  42°  C  and  allowed  to  harden  in  ten  centimeter 
jictri  dishe-s.  To  prevent  condensation  it  was  found  best  to  cover 
with  sterile  tile  covers.  After  hardening  three  methods  of 
inoculation  ■were  tried. 

a.  Two  separate  streaks  were  made  with  a  loop  full  of  saline 
suspension,  one  on  cithei-  side  of  the  diameter  of  the  plate.  Half 
of  the  plate  was  then  exposed,  the  other  half  being  protected  by 
a  glass  cover,  covered  with  black  paper.     The  plate  was  then 


li'li'I    Han-is-lloijl:  Aclioii  of  I'llrariolcl  Lif/lit  on  Barleria      247 

ineubated  twcjily-iuur  lioiuvs,  and  tliu  colonics  were  identified 
directly,  or,  in  siispicioiLs  eases,  smears  were  made.  The  objection 
to  this  method  was  that  there  was  no  certainty  tliat  the  control 
streak  and  the  exposed  streak  were  similarly  inoevdated. 

/;.  To  overcome  this  objection  a  single  large  streak  in  the  shai)e 
of  the  letter  "Z"  was  made  of  one  loopfnl  of  bacterial  suspension, 
and  half  the  plate  exposed  as  before. 

(■.  Another  plating  method  experimented  with  was  to  flood 
the  entire  plate  with  a  definite  amount  of  saline  suspension  and 
then  expose  one  side,  as  in  the  above. 

Plating  methods  were  also  abandoned  finally  because  they  did 
not  yield  uniform  results,  due  undoubtedly  to  some  oi-ganisms 
getting  in  under  the  agar  and  being  protected  by  the  protein 
material. 

The  method  finally  employed  was  a  cover  slip  method  suggested 
by  Professor  Ivan  C.  Hall.  Upon  one  .surface  of  a  sterile  cover 
.slip  one  loopful  of  saline  suspension  of  a  twenty-four  hour  agar 
growth  was  placed  and  allowed  to  dry  in  a  sterili>  peti'i  dish. 
Assuming  the  saline  suspension  to  be  uniform  each  cover  slip 
therefore  had  approximately  the  same  number  of  organisms. 
When  dry  the  cover  slips  were  exposed  directly  to  the  rays  by 
placing  them  in  a  petri  di.sh  12  cm.  below  the  arc  of  the  Cooper- 
Hewitt  machine.  After  the  given  exposure  the  cover  slip  was 
picked  up  with  sterile  forceps,  dropped  into  a  tube  of  broth, 
the  broth  was  incubated  for  forty-eight  hours,  and  the  results 
observed.  The  growth  of  these  three  organisms  in  broth  is  quite 
characteristic,  and  no  further  examination  was  usually  necessary. 
In  doubtful  eases  agar  plates  were  streaked  from  the  broth  and 
the  organisms  were  identified  by  the  usual  methods. 

The  exposures  varied  from  five  seconds  to  200  seconds.  Some- 
what over  100  exposures  were  made,  and  although  there  were 
slight  discrepancies  in  the  results,  due  to  the  objections  mentioned 
to  plating  methods,  consistent  results  were  obtained  by  the  cover 
slip  method,  so  that  we  may  definitely  say  that : 

Bacillus  mucosus  capsulatus  was  killed  after  20  seconds. 
Staphylococcus  "       "         "      90       " 

B.  suhtilis  "       "         "150      " 


248  JJniversitij  of  Valifoviiia  PuhUcaiionsin  Paflioloyij   [Vol.2 

These  figrires  represent  the  relative  resistance  of  these  three 
organisms. 

The  protective  action  of  tlie  amino  acids  was  then  studied. 
The  cover  slips  were  exposed  as  before,  but  between  the  cover 
slip  and  the  arc  a  quartz  beaker  containing  the  given  amino  acid 
was  interposed,  so  that  the  rays  before  striking  the  organisms 
passed  through  the  amino  acids.  The  results  obtained  confirm 
our  previous  work.  With  B.  suhtilis,  whose  normal  extermina- 
tion period  is  150  seconds,  we  found  exposure  for  forty  minutes 
to  ultraviolet  light  passed  through  1%  tyrosin  solution  exerted 
no  toxic  effect  upon  the  bacilli,  a  good  growth  being  obtained  in 
forty-eight  hours.  Similarly,  Staphylococcus  aureus  gave  good 
growth  after  forty  minutes;  B.  mucosus  cwpsulafus,  though  not 
tested  after  longer  exposure,  gave  satisfactory  growth  after  ten 
minutes. 

A  good  growth  was  also  obtained  with  amino-benzoic  acid 
after  exposure  of  these  organisms  for  3200  seconds  to  ultraviolet 
light  detoxicated  by  passing  through  this  substance.  Phenyla- 
lanin  could  not  be  secured,  but  there  is  little  doubt  that  similar 
results  could  be  obtained  with  it. 

These  re.sults  confirm  those  of  our  previou.s  report*'''  and 
indicate  that  the  aromatic  amino-aeid  radicals  are  the  absorbing 
substances  in  bacteria  as  well  as  in  protozoa.  Kober's"  work 
placed  the  absorption  band  for  tyrosin  at  248  to  297/i,  or  2480- 
2970  Angstrom  units,  of  wave  length,  and  for  phenylalanin  236- 
27  V,  or  2360-2710  Angstrom  units. 

Therefore  ultraviolet  light,  of  wave  lengths  2360-2970  Ang- 
strom units,  should  contain  practically  all  of  the  rays  toxic  for 
protopla.sm.  Two  recent  papers  have  appeared,  however,  which 
report  different  results.  Browning  and  Russ"  found  the  toxic 
action  of  ultraviolet  light  falling  off  sharply  at  2960  A. U..  which 
would  apparently  correspond  with  one  edge  of  the  tyrosine  band. 
The\'  report,  however,  an  apparently  constant  toxicity  from 
2960-2100  A.U.,  and  did  not  investigate  below  2100  A.U.  New- 
comer'*-" reported  also  a  constant  toxicity  from  2100  A.U.  up  to 
a  little  less  than  21)00  A.U.,  the  toxicity  falling  off  to  practically 
zero  at  2970  A.U.    The  region  in  which  tyrosine  and  phenylalanin 


1919]    Harris-lloi/l  ■  Ad  ion  tif  UUraviolet  Light  on  Bacteria     2V.) 

are  both  absorbed,  i.e.  :i48U  to  2710  A. II.,  should  be  tlie  most 
toxic  for  protoplasm,  whereas  the  region  containing  wave  lengths 
shorter  than  2300  A. U.  should  be  relatively  non-toxic. 

Our  former  experiments  eonelusively  demoiistrated  that  a 
solution  of  tyrosine  will  absorb  practically  all  of  the  toxic  rays, 
those  getting  through  not  being  sufficiently  toxic  to  kill  paramecia 
after  exposure  for  forty  minutes,  whereas  if  the  rays  absorbed 
by  tyrosine  were  allowed  to  act  the  paramecia  were  killed  in 
100  seconds. 

Conclusions 

1.  The  aromatic  amino  acid  radicals  are  among  the  sub- 
stances in  bacteria  affected  by  the  action  of  ultraviolet  light,  as 
was  shown  for  paramecium  in  a  previous  report. 

2.  The  ultraviolet  radiations  produced  by  the  mercury  arc  of 
wave  lengths  not  aljsorbed  by  tyrosine  and  phenylalanin  are 
relatively  non-toxic.  Therefore,  using  Kober's  determinations 
for  the  wave  lengths  corresponding  to  these  two  absorption  bands, 
the  ultraviolet  radiations  which  are  toxic  for  protopla.sm  are  of 
wave  lengths  from  2480-2710  A.U. 

3.  In  the  three  types  of  bacteria  studied  capsulated  organisms 
were  found  to  be  most  susceptible  and  sporulating  organisms 
most  resistant  to  the  action  of  ultraviolet  light.  The  work  sug- 
gests strongly  that  the  protoplasm  of  Bacillus  mucosus  capsulatus 
contains  greater  amounts  of  the  above  mentioned  substances  than 
the  non-capsulated  staphylococcus  and  the  sporulating  hay 
bacillus. 

Transmitted  Fehruanj  6,  1919. 


250         Unii-crsifi/  of  Califuniia  rublicationsin  Pathology   [Vol.  2 


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*.  5  Harris,  F.  I.,  and  Hoyt,  H.  S.  The  Possible  Origin  of  the  Toxicity 
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TTNlVEESITY  OF  OALITOENIA  PUBLICATIONS— (Oontlnnod) 

11.  A  Stable  Medium  for  the  Production  of  Potent  Tetanus  Toxin,  by 

Ivan  C.  Hall.    Pp.  97-102.     August  30,  1913   05 

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15.  Forensic  Value  of  the  Precipitin  Test  in  the  Enforcement  of  the  Game 

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16.  Studies  on  the  Locus  of  Antibody  Formation  II.  The  Effect  of  Benzol 

Intoxication  and  Consequent  Leucopenia  on  the  Formation  of  Arti- 
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Proteins,  by  Carl  L.  A.  Schmidt.    Pp.  157-204.    August,  1916 50 

19.  An  Investigation  of  the  Batio  of  Globulins  to  Albumins  in  the  Blood- 

Serum  of  Normal  Rabbits  aad  of  Rabbits  Immunized  Against  Bar 
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Man,  by  Carl  L.  A.  Schmidt  and  D.  R.  Hoagland.  Pp.  215-244. 
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21.  The  Action  of  Ultraviolet  Light  on  Certain  Bacteria  in  Relation  to 

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PHYSIOLOGY.— S.  S.  Maxwell,  Editor.    Price  per  volume  ?2.    Volumes  I  (pp.  217),  U  (pp. 
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Pp.  1-4.    September,  1910  _ _ - .05 

2.  On  the  Rise  of  Temperature  in  Rabbits,  caused  by  the  Injection  of  Salt 

Solutions,  by  Theo.  C.  Biumett.    Pp.  5-7.    September,  1910  .05 

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September,  1910  -. .05 

4.  Galvanotropic  Orientation  in  Gonlum  Pectorale,  by  A,  B.  Moore  aad 

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5.  On  a  Possible  Source  of  the  Biological  Individuality  of  the  Tissues  and 

Tissue-fluids  of  Animal  Species,  by  T.  Brailsford  Eobertson.  Pp. 
25-30.     May,  1911    _ — _ — -       .06 

6.  Some  Factors  Influencing  the  Quantitative  Determination  of  Gliadin, 

by  J.  E.  Greaves.    Pp.  31-74.    August,  1911  40 

7.  Errors  in  Refraction  Occurring  in  the  Students  of  the  University  of 

California,  by  Theo.  0.  Burnett.    Pp.  75-77.    August,  1911  06 

8.  On  the  CytoUtic  Action  of  Ox-Blood  Serum  upon  Sea-urchin  Eggs,  and 

Its  Inhibition  by  Proteins,  by  T.  Brailsford  Eobertson.  Pp.  79-88. 
February,   1912    - 10 

9.  On  the  Nature  of  the  Cortical  Layer  in  Sea-urchin  Eggs,  by  A.  B. 

Moore.    Pp.  89-90. 

10.  On  the  Nature  of  the  Sensitization  of  Sea-urchin  Eggs  by  Strontium 

Chloride,  by  A.  R.  Moore.    Pp.  91-93. 

Nos.  9  and  10  in  one  cover.    March,  1912  06 

11.  On  the  Isolation  of  Oocytase,  the  Fertilizing  and  Cytolyzlng  Substance 

in  Mammalian  Blood  Sera,  by  T.  Brailsford  Robertson.    Pp.  95-102. 

12.  On  the  Extraction  of  a  Substance  from  the  Sperm  of  the  Sea-urchla 

(Strongylocentrotus  pwr-puratus)  which  will  Fertilize  the  Eggs  of  that 
Species,  by  T.  Brailsford  Robertson.    Pp.  103-105. 
IS.  The  Demonstration  of  "Masked"  Iron  In  Blood,  by  C.  B.  Bennett. 
Pp.  107-108. 

Nos.  11,  12.  and  13  In  one  cover.    March,  1912  „ „ 10 


14.  . 
15. 


lUnued) 
aodeims,  by  A. 

Iiivlng  Muscle? 


05 

]  Glucase,  a  New 

j-183.    September 

t ''^ 

]  ryclmine,  by  A.  B. 

mooic.  — ^ 1. 05 

18.  On  the  Volume  Changes  in  tEe  Timr -m.™-^ inilar  Exercise,  by 

Esther  V.  Starkweather.    Pp.  187-200.    October,  1913  15 

19.  The    Blood-pressure    Effects    of   the   Application   of   Creatin   to   the 

Cerebral  Cortex,  by  E.  S.  Sherman.    Pp.  201-206,  plate  1.    Septem- 
ber, 1914  _ 05 

20.  A  Comparison  of  the  Weights  at  Birth  of  British  Infants  Bom  in  the 

British  Isles,  the  United  States,  and  Australia   (Preliminary  Com- 
munication), by  T.  Brailsford  Eobertson.    Pp.  207-210.    January,  1915      .05 

21.  Tables  for  the  Computation  of  Curves  of  Autocatalysis,  with  Especial 

Reference  to  Curves  of  Growth,  by  T.  Brailsford  Robertson.    Pp.  211- 

228.    March,  1915 20 

Vol.  5.  1.  The  Effect  of  Lecithin  and  Cholesterol  upon  the  Division  Rate  of  Para- 
mecium, by  AUne  Browder.    Pp.  1-3.    September,  1915  05 

2.  The  Simultaneous  Administration  of  Pituitary  and  Thymus  to  Growing 

Chicks,  by  Samuel  S.  Maxwell.    Pp.  5-8.    March,  1916  05 

3.  The  Growth  of  Normal  and  Hypophysectomized  Tadpoles  as  Influenced 

by  Endocrine  Diets,  by  P.  E.  Smith.     Pp.  11-22,  2  figures  in  text. 
April,   1918   15 

4.  Table  of  Ph,  H+  and  OH-  Values  Corresponding  to  Electromotive  Forces 

Determined  in  Hydrogen  Electrode  Measurements,  with  a  Bibliog- 
raphy, by  Carl  L.  A.  Schmidt  and  D.  R.  Hoagland.     Pp.  23-68... (7/(  press) 

MEMOIRS  OF  THE  UNIVERSITY  OF  CALIFORNIA  (Quarto). 

Vol.  1.  1.  Triassic  Ichthyosaurla,  with  special  reference  to  the  American  Forms, 
by  John  C.  Merriam.  Pp.  1-196,  plates  1-18,  154  test  figures.  Sep- 
tember, 1908  $3.00 

2.  The  Fauna  of  Rancho  La  Brea.  Part  1,  Occurrence,  by  John  C.  Mer- 
riam.   Pp.  197-213,  plates  19-23.    November,  1911  30 

The  Favma  of  Rancho  La  Brea.    Part  2,  Canidae,  by  John  C.  Merriam. 

Pp.  215-272,  plates  24-28,  35  text  figures.    October,  1912 80 

Vol.  2.    The  Silva  of  California,  by  Willis  Linn  Jepson.    480  pages,  85  plates,  3 

maps.    December,  1910.    Cloth  $7.50,  paper „ 5.00 

Vol.  3.    Business  Cycles,   by  Wesley  C.  MitcheU.     xviii  +  610  pages,   with  77 

charts.    September,  1913.    Cloth,  $7.50,  paper  5.00 

Vol,  4.  1.  The  Battle  of  the  Seven  Arts;  a  French  Poem  by  Henri  d'Andell, 
Trouvere  of  the  Thirteenth  Century.  Edited  and  Translated,  with 
Introduction  and  Notes,  by  Louis  J.  Paetow.    July,  1914  75 

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Psychology,  Semitic  Philology,  Zoology. 

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